Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/13—Electrodes for accumulators with non-aqueous electrolyte, e.g. for lithium-accumulators; Processes of manufacture thereof
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0567—Liquid materials characterised by the additives
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/052—Li-accumulators
  • H01M10/0525—Rocking-chair batteries, i.e. batteries with lithium insertion or intercalation in both electrodes; Lithium-ion batteries
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/05—Accumulators with non-aqueous electrolyte
  • H01M10/056—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes
  • H01M10/0564—Accumulators with non-aqueous electrolyte characterised by the materials used as electrolytes, e.g. mixed inorganic/organic electrolytes the electrolyte being constituted of organic materials only
  • H01M10/0566—Liquid materials
  • H01M10/0569—Liquid materials characterised by the solvents
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M10/00—Secondary cells; Manufacture thereof
  • H01M10/42—Methods or arrangements for servicing or maintenance of secondary cells or secondary half-cells
  • H01M10/4235—Safety or regulating additives or arrangements in electrodes, separators or electrolyte
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M4/62—Selection of inactive substances as ingredients for active masses, e.g. binders, fillers
  • H01M4/621—Binders
  • H01M4/622—Binders being polymers
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01M—PROCESSES OR MEANS, e.g. BATTERIES, FOR THE DIRECT CONVERSION OF CHEMICAL ENERGY INTO ELECTRICAL ENERGY
  • H01M4/00—Electrodes
  • H01M4/02—Electrodes composed of, or comprising, active material
  • H01M2004/026—Electrodes composed of, or comprising, active material characterised by the polarity
  • H01M2004/027—Negative electrodes
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02E—REDUCTION OF GREENHOUSE GAS [GHG] EMISSIONS, RELATED TO ENERGY GENERATION, TRANSMISSION OR DISTRIBUTION
  • Y02E60/00—Enabling technologies; Technologies with a potential or indirect contribution to GHG emissions mitigation
  • Y02E60/10—Energy storage using batteries

Definitions

• This application relates to the field of energy storage, specifically to an electrochemical apparatus and an electronic apparatus, and in particular to a lithium-ion battery.
• electrochemical apparatuses for example, lithium-ion batteries
• the lithium-ion batteries have the advantages of high energy density, long cycle life, and environment friendliness.
• challenges in application of the lithium-ion batteries in terms of, for example, endurance mileage, costs, charge performance, safety performance, and climbing performance. Improving the rate performance of the lithium-ion batteries usually increases the temperature of the lithium-ion batteries and degrades safety performance of the lithium-ion batteries.
• Embodiments of this application provide an electrochemical apparatus and an electronic apparatus that have improved rate performance and safety performance, so as to resolve at least one problem existing in the related fields to at least some extent.
• the negative electrode includes a negative electrode current collector and a negative electrode mixture layer formed on the negative electrode current collector, and the negative electrode mixture layer includes a negative electrode active substance.
• An elongation at a yield point of the negative electrode mixture layer is X%, a median particle size of the negative electrode active substance is Y ⁇ m, and X and Y satisfy: 0.1 ⁇ X/Y ⁇ 30.
• the electrolyte includes a compound having a cyano group.
• X is within a range of 10 to 30, and Y is within a range of 1 to 50.
• a content percentage of the compound having the cyano group is Z%, and Z is within a range of 0.1 to 10.
• X and Z satisfy: 2 ⁇ X/Z ⁇ 100.
• the negative electrode mixture layer includes rubber, and the rubber includes at least one of styrene-butadiene rubber, isoprene rubber, butadiene rubber, fluorine rubber, acrylonitrile-butadiene rubber, and styrene-propylene rubber.
• the rubber further includes at least one of an acrylic functional group, a chlorotrifluoroethylene functional group, or a hexafluoropropylene functional group.
• the negative electrode active substance has at least one of the following characteristics:
• metal including at least one of molybdenum, iron, or copper, and based on a weight of the negative electrode mixture layer, a content percentage of the metal is less than 0.05%.
• the compound having the cyano group includes at least one of succinonitrile, glutaronitrile, adiponitrile, 1, 5-dicyanopentane, 1, 6-dicyanohexane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 2, 4-dimethylglutaronitrile, 2, 2, 4, 4-tetramethylglutaronitrile, 1, 4-dicyanopentane, 1, 2-dicyanobenzene, 1, 3-dicyanobenzene, 1, 4-dicyanobenzene, ethylene glycol bis (propionitrile) ether, 3, 5-dioxa-heptanedionitrile, 1, 4-bis (cyanoethoxy) butane, diethylene glycol di (2-cyanoethyl) ether, triethylene glycol di (2-cyanoethyl) ether, tetraethylene glycol di (2-cyanoethyl) ether, 1, 3-di (2-cyanoe
• the compound having the cyano group includes an ether bond-free dinitrile compound and an ether bond-containing dinitrile compound, and a content percentage of the ether bond-free dinitrile compound is greater than a content percentage of the ether bond-containing dinitrile compound.
• the compound having the cyano group includes a dinitrile compound and a trinitrile compound, and a content percentage of the dinitrile compound is greater than a content percentage of the trinitrile compound.
• the compound having the cyano group includes a dinitrile compound and a trinitrile compound having an ether bond, and a content percentage of the dinitrile compound is greater than a content percentage of the trinitrile compound having the ether bond.
• the electrolyte further includes at least one of the following compounds:
• R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 each are independently hydrogen or C 1 -C 10 alkyl
• L 1 and L 2 each are independently - (CR 7 R 8 ) n -;
• R 7 and R 8 each are independently hydrogen or C 1 -C 10 alkyl
• n 1, 2, or 3.
• the compound of Formula 1 includes at least one of the following compounds:
• a content percentage of the compound of Formula 1 is within a range of 0.01%to 5%.
• a content percentage of the fluoroethylene carbonate is b%, and b is within a range of 0.1 to 10.
• a relationship between Y and b satisfies 4 ⁇ Y ⁇ b ⁇ 200.
• this application provides an electronic apparatus, including the electrochemical apparatus according to this application.
• a list of items connected by the term "at least one of” may mean any combination of the listed items.
• the phrase "at least one of A and B” means only A, only B, or both A and B.
• the phrase "at least one of A, B, and C” means only A, only B, only C, A and B (excluding C) , A and C (excluding B) , B and C (excluding A) , or all of A, B, and C.
• Item A may include one element or a plurality of elements.
• Item B may include one element or a plurality of elements.
• Item C may include one element or a plurality of elements.
• the term "at least one type of" has the same meaning as the term "at least one of” .
• alkyl group is intended to be a linear saturated hydrocarbon structure having 1 to 20 carbon atoms. "Alkyl group” is also intended to be a branched or cyclic hydrocarbon structure having 3 to 20 carbon atoms. When an alkyl group having a specific carbon quantity is specified, all geometric isomers having the carbon quantity are intended to be included.
• a butyl group means to include an n-butyl group, a sec-butyl group, an isobutyl group, a tert-butyl group, and a cyclobutyl group
• a propyl group includes an n-propyl group, an isopropyl group, and a cyclopropyl group.
• alkyl group examples include, but are not limited to, a methyl group, an ethyl group, an n-propyl group, an isopropyl group, an cyclopropyl group, an n-butyl group, an isobutyl group, a sec-butyl group, a tert-butyl group, a cyclobutyl group, an n-pentyl group, an isopentyl group, a neopentyl group, a cyclopentyl group, a methylcyclopentyl group, an ethylcyclopentyl group, an n-hexyl group, an isohexyl group, a cyclohexyl group, an n-heptyl group, an octyl group, a cyclopropyl group, a cyclobutyl group, a norbornyl group, and the like.
• halogenated means that hydrogen atoms in a group are partially or entirely substituted with halogen atoms (for example, fluorine, chlorine, bromine, or iodine) .
• electrochemical apparatuses for example, lithium-ion batteries
• people impose higher requirements on performance of the electrochemical apparatuses, including the rate performance and safety performance.
• rate performance of the lithium-ion batteries is improved by means of selecting a positive or negative electrode active substance, electrolyte composition, and optimized battery design.
• the lithium-ion batteries easily generate a great amount of heat during high-rate discharging, imposing an adverse impact on the safety performance of the lithium-ion batteries.
• a relationship between an elongation at a yield point of a negative electrode mixture layer and a median particle size (D50) of the negative electrode active substance is adjusted and an electrolyte that contains a compound having a cyano group is also used, so as to make an electrochemical apparatus have lower internal resistance, higher adhesion, higher conductivity, and larger compacted density, thereby significantly improving the rate performance of the electrochemical apparatus while reducing a thickness swelling rate of the electrochemical apparatus under thermal abuse to improve the safety performance of the electrochemical apparatus.
• this application provides an electrochemical apparatus, including a positive electrode, a negative electrode, and an electrolyte as described less than.
• the negative electrode includes a negative electrode current collector and a negative electrode mixture layer formed on one or both surfaces of the negative electrode current collector, and the negative electrode mixture layer includes a negative electrode active substance.
• the electrochemical apparatus in this application is characterized in that the elongation at the yield point of the negative electrode mixture layer X%and the D50 Y ⁇ m of the negative electrode active substance satisfy: 0.1 ⁇ X/Y ⁇ 30. In some embodiments, 0.5 ⁇ X/Y ⁇ 25. In some embodiments, 1 ⁇ X/Y ⁇ 20. In some embodiments, 3 ⁇ X/Y ⁇ 15. In some embodiments, X/Y is 0.1, 0.5, 1, 2, 5, 8, 10, 12, 15, 18, 20, 25, 30, or within a range between any two of the foregoing values. When the elongation X%of the yield point of the negative electrode mixture layer and the D50 Y ⁇ m of the negative electrode active substance satisfy the foregoing relationship, the rate performance and the safety performance of the electrochemical apparatus can be significantly improved.
• the elongation at the yield point of the negative electrode mixture layer may be expressed by the following formula: (Stretching length of the negative electrode mixture layer at the yield point–Original length of the negative electrode mixture layer) /Original length of the negative electrode mixture layer ⁇ 100%.
• the elongation at the yield point of the negative electrode mixture layer can be determined by using the following method: attaching a 50 ⁇ m-thick polyethylene glycol terephthalate (PET) film to one adhesive surface of a double-sided adhesive tape and attaching the negative electrode mixture layer to the other adhesive surface of the double-sided adhesive tape; removing the negative electrode mixture layer and the PET film together from the negative electrode current collector to obtain a to-be-tested sample; taking a 140mm-long and 15mm-wide sample to be tested and fastening the sample onto a clamping plate (a positioning fixture) of a tensile tester, to make a length of a stretchable part of the negative electrode mixture layer reach 100mm; in a room temperature environment (20°C ⁇ 5°C) , stretching the to-be-tested sample in a direction that is substantially orthogonal to a thickness direction of the negative electrode mixture layer (for ⁇ 10° along the direction orthogonal to the thickness direction) ; each time the negative electrode mixture layer is stretched by 1mm (the elong
• the negative electrode mixture layer may be one or more layers, and each of the plurality of layers of negative electrode active substances may contain the same or different negative electrode active substances.
• the negative electrode active substance is any material capable of reversibly intercalating and deintercalating metal ions such as lithium ions.
• a rechargeable capacity of the negative electrode active substance is greater than a discharge capacity of the positive electrode active substance to prevent lithium metal from accidentally precipitating onto the negative electrode during charging.
• the elongation at the yield point of the negative electrode mixture layer is within a range of 10%to 30%. In some embodiments, the elongation at the yield point of the negative electrode mixture layer is within a range of 15%to 25%.
• the elongation at the yield point of the negative electrode mixture layer is 10%, 12%, 15%, 18%, 20%, 22%, 25%, 28%, 30%, or within a range between any two of the foregoing values.
• the rate performance and the safety performance of the electrochemical apparatus can be further improved.
• the median particle size (D50) of the negative electrode active substance is within a range of 1 ⁇ m to 50 ⁇ m. In some embodiments, the median particle size (D50) of the negative electrode active substance is within a range of 3 ⁇ m to 40 ⁇ m. In some embodiments, the median particle size (D50) of the negative electrode active substance is within a range of 5 ⁇ m to 30 ⁇ m. In some embodiments, the median particle size (D50) of the negative electrode active substance is within a range of 10 ⁇ m to 20 ⁇ m.
• the median particle size of the negative electrode active substance is 1 ⁇ m, 5 ⁇ m, 10 ⁇ m, 15 ⁇ m, 20 ⁇ m, 25 ⁇ m, 30 ⁇ m, 35 ⁇ m, 40 ⁇ m, 45 ⁇ m, 50 ⁇ m, or within a range between any two of the foregoing values.
• D50 median particle size
• the median particle size (D50) of the negative electrode active substance can be measured by using the following method: dispersing a carbon material in a 0.2%aqueous solution (about 10mL) of polyoxyethylene (20) sorbitan monolaurate, and using a laser diffraction/scattering particle size distribution analyzer (LA-700 manufactured by Horiba) to conduct testing.
• the negative electrode mixture layer includes rubber.
• the rubber can effectively improve interface stability of the negative electrode mixture layer, thereby significantly improving the rate performance and safety performance of the electrochemical apparatus.
• the rubber includes at least one of styrene-butadiene rubber, isoprene rubber, butadiene rubber, fluorine rubber, acrylonitrile-butadiene rubber, and styrene-propylene rubber.
• the rubber further includes at least one of an acrylic functional group, a chlorotrifluoroethylene functional group, or a hexafluoropropylene functional group.
• a content percentage of the rubber is less than 10%. In some embodiments, based on a weight of the negative electrode mixture layer, a content percentage of the rubber is less than 8%. In some embodiments, based on a weight of the negative electrode mixture layer, a content percentage of the rubber is less than 5%. In some embodiments, based on a weight of the negative electrode mixture layer, a content percentage of the rubber is less than 3%. In some embodiments, based on a weight of the negative electrode mixture layer, a content percentage of the rubber is less than 2%.
• the negative electrode active substance has at least one of the following characteristics (i) or (ii) :
• the negative electrode active substance includes at least one of artificial graphite, natural graphite, mesophase carbon microsphere, soft carbon, hard carbon, amorphous carbon, silicon-containing material, tin-containing material, and an alloy material.
• the shape of the negative electrode active substance includes but is not limited to fibrous, spherical, granular, and scaly.
• the negative electrode active substance includes a carbon material.
• the negative electrode active substance has a specific surface area of less than 5m 2 /g. In some embodiments, the negative electrode active substance has a specific surface area of less than 3m 2 /g. In some embodiments, the negative electrode active substance has a specific surface area of less than 1m 2 /g. In some embodiments, the negative electrode active substance has a specific surface area of greater than 0.1m 2 /g. In some embodiments, the negative electrode active substance has a specific surface area of greater than 0.7m 2 /g. In some embodiments, the negative electrode active substance has a specific surface area of greater than 0.5m 2 /g.
• the specific surface area of the negative electrode active substance is within a range between any two of the foregoing values.
• the specific surface area of the negative electrode active substance falls within the foregoing range, lithium deposition on the electrode surface can be suppressed, and gas generation resulting from reaction of the negative electrode with the electrolyte can be suppressed.
• the specific surface area (BET) of the negative electrode active substance can be measured by using the following method: using a surface area meter (a full-automatic surface area measuring device manufactured by OHKURA or RIKEN) to perform pre-drying on the sample at 350°C for 15 minutes when nitrogen flows, using a nitrogen-helium mixed gas whose relative pressure value of nitrogen is accurately adjusted to 0.3 with respect to atmospheric pressure, and conducting tests by using the nitrogen adsorption BET single-point method for air flow.
• a surface area meter a full-automatic surface area measuring device manufactured by OHKURA or RIKEN
• an inter-layer distance of a lattice plane (002 plane) of the negative electrode active substance is within a range of about 0.335nm to about 0.360nm, within a range of about 0.335nm to about 0.350nm, or within a range of about 0.335nm to about 0.345nm.
• a crystallite size (Lc) of the negative electrode active substance is greater than about 1.0nm or greater than about 1.5nm.
• a Raman R value of the negative electrode active substance is greater than about 0.01, greater than about 0.03, or greater than about 0.1. In some embodiments, a Raman R value of the negative electrode active substance is less than about 1.5, less than about 1.2, less than about 1.0, or less than about 0.5. In some embodiments, a Raman R value of the negative electrode active substance is within a range between any two of the foregoing values.
• a Raman half-peak width of the negative electrode active substance near 1580cm -1 is not particularly limited. In some embodiments, a Raman half-peak width of the negative electrode active substance near 1580cm -1 is greater than 10cm -1 or greater than 15cm -1 . In some embodiments, a Raman half-peak width of the negative electrode active substance near 1580cm -1 is less than about 100cm -1 , less than about 80cm -1 , less than about 60cm -1 , or less than about 40cm -1 . In some embodiments, a Raman half-peak width of the negative electrode active substance near 1580cm -1 is within a range between any two of the foregoing values.
• a length-to-thickness ratio of the negative electrode active substance is greater than about 1, greater than about 2, or greater than about 3. In some embodiments, a length-to-thickness ratio of the negative electrode active substance is less than about 10, less than about 8, or less than about 5. In some embodiments, a length-to-thickness ratio of the negative electrode active substance is within a range between any two of the foregoing values. When the length-to-thickness ratio of the negative electrode active substance falls within the foregoing range, coating can be more uniform.
• the negative electrode active substance includes a metal
• the metal includes at least one of molybdenum, iron, or copper. These metal elements can react with some organic substances having poor conductivity in the negative electrode active substance, thereby facilitating film formation on the surface of the negative electrode active substance.
• the metal elements are present in trace amounts in the negative electrode mixture layer to prevent non-conductive by-products from forming and adhering to the surface of the negative electrode.
• a content percentage of the metal is less than 0.05%.
• a content percentage of the metal is less than 0.04%.
• a content percentage of the metal is less than 0.03%.
• a content percentage of the metal is less than 0.01%.
• the negative electrode mixture layer further includes at least one of a silicon-containing material, a tin-containing material, and an alloy material. In some embodiments, the negative electrode mixture layer further includes at least one of a silicon-containing material and a tin-containing material. In some embodiments, the negative electrode mixture layer further includes one or more of a silicon-containing material, a silicon-carbon composite material, a silicon-oxide material, an alloy material, and a lithium-containing metal composite oxide material.
• the negative electrode mixture layer further includes other types of negative electrode active substances, for example, one or more materials that contain a metal element and a metalloid element capable of forming an alloy with lithium.
• examples of the metal element and the metalloid element include, but are not limited to, Mg, B, Al, Ga, In, Si, Ge, Sn, Pb, Bi, Cd, Ag, Zn, Hf, Zr, Y, Pd, and Pt.
• examples of the metal and metalloid elements include Si, Sn, or a combination thereof. Si and Sn have an excellent capability of deintercalating lithium ions, and can provide a high energy density for the lithium-ion batteries.
• other types of negative electrode active substances may further include one or more of a metal oxide and a polymer compound.
• the metal oxide includes but is not limited to iron oxide, ruthenium oxide, and molybdenum oxide.
• the polymer compounds include, but are not limited to, polyacetylene, polyaniline, and polypyrrole.
• the negative electrode mixture layer further includes a negative electrode conductive material
• the conductive material may include any conductive material provided that the conductive material does not cause a chemical change.
• Non-limitative examples of the conductive material include a carbon-based material (for example, natural graphite, artificial graphite, carbon black, acetylene black, Ketjen black, or carbon fiber) , a conductive polymer (for example, a polyphenylene derivative) , and a mixture thereof.
• the negative electrode mixture layer further includes the negative electrode binder.
• the negative electrode binder can improve binding between particles of the negative electrode active substance and binding between the negative electrode active substance and the current collector.
• the type of the negative electrode binder is not particularly limited provided that the binder is a material that is stable to the electrolyte or the solvent used in manufacturing of the electrode.
• the negative electrode binder examples include, but are not limited to, a resin-based polymer such as polyethylene, polypropylene, polyethylene glycol terephthalate, polymethyl methacrylate, aromatic polyamide, polyimide, cellulose, or nitrocellulose; a rubber polymer such as styrene-butadiene rubber (SBR) , isoprene rubber, polybutadiene rubber, fluorine rubber, acrylonitrile ⁇ butadiene rubber (NBR) , or ethylene ⁇ propylene rubber; styrene ⁇ butadiene ⁇ styrene block copolymer or hydride thereof; a thermoplastic elastomeric polymer such as ethylene ⁇ propylene ⁇ diene terpolymer (EPDM) , styrene ⁇ ethylene ⁇ butadiene ⁇ styrene copolymer, styrene ⁇ isoprene ⁇ styrene block copolymer or hydride thereof; a soft resinous poly
• a content percentage of the negative electrode binder is greater than about 1%, greater than about 2%, or greater than about 3%. In some embodiments, based on the weight of the negative electrode mixture layer, a content percentage of the negative electrode binder is less than about 10%, less than about 8%, or less than about 5%. Based on the weight of the negative electrode mixture layer, a content percentage of the negative electrode binder is within a range between any two of the foregoing values.
• the type of the solvent used for forming the negative electrode slurry is not particularly limited provided that the solvent is capable of dissolving or dispersing the negative electrode active substance, the negative electrode binder, and the thickener and the conductive material that are used as required.
• the solvent used for forming the negative electrode slurry may be any one of an aqueous solvent and an organic solvent. Examples of the aqueous solvent may include, but are not limited to, water, alcohol, and the like.
• organic solvent may include, but are not limited to, N-methylpyrrolidone (NMP) , dimethylformamide, dimethylacetamide, methyl ethyl ketone, cyclohexanone, methyl acetate, methyl acrylate, diethyltriamine, N, N-dimethylaminopropylamine, tetrahydrofuran (THF) , toluene, acetone, diethyl ether, hexamethylphosphoramide, dimethyl sulfoxide, benzene, xylene, quinoline, pyridine, methylnaphthalene, hexane, and so on.
• NMP N-methylpyrrolidone
• dimethylformamide dimethylacetamide
• methyl ethyl ketone cyclohexanone
• methyl acetate methyl acrylate
• diethyltriamine N, N-dimethylaminopropylamine
• THF
• the thickener is usually used to adjust viscosity of the negative electrode slurry.
• the type of the thickener is not particularly limited, and examples of the thickener may include, but are not limited to, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, salt thereof, and the like.
• the thickener may be used alone or in any combination.
• a content percentage of the thickener is greater than about 0.1%, greater than about 0.5%, or greater than about 0.6%. In some embodiments, based on the weight of the negative electrode mixture layer, the content percentage of the thickener is less than about 5%, less than about 3%, or less than about 2%. When the content percentage of the thickener falls within the foregoing range, a decrease in the capacity of the electrochemical apparatus and an increase in the resistance can be suppressed, and good coating of the negative electrode slurry can be ensured.
• a substance different from a composition of the negative electrode mixture layer may be adhered to the surface of the negative electrode mixture layer.
• the surface adhesion substance of the negative electrode mixture layer include, but are not limited to, oxides such as aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulphates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; and carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate.
• the content percentage of the negative electrode active substance is greater than about 80%, greater than about 82%, or greater than about 84%. In some embodiments, based on the weight of the negative electrode mixture layer, the content percentage of the negative electrode active substance is less than about 99%or less than about 98%. In some embodiments, based on the weight of the negative electrode mixture layer, the content percentage of the negative electrode active substance is within a range between any two of the foregoing values.
• the density of the negative electrode active substance in the negative electrode mixture layer is greater than about 1g/cm 3 , greater than about 1.2g/cm 3 , or greater than about 1.3g/cm 3 . In some embodiments, the density of the negative electrode active substance in the negative electrode mixture layer is less than about 2.2g/cm 3 , less than about 2.1g/cm 3 , less than about 2.0g/cm 3 , or less than about 1.9g/cm 3 . In some embodiments, the density of the negative electrode active substance in the negative electrode mixture layer is within a range between any two of the foregoing values.
• the negative electrode current collector may use any known current collector.
• the negative electrode current collector include, but are not limited to, metal materials such as aluminum, copper, nickel, stainless steel, and nickel plated steel. In some embodiments, the negative electrode current collector is copper.
• the negative electrode current collector may be in forms including but not limited to a metal foil, a metal cylinder, a metal coil, a metal plate, a metal foil, a sheet metal mesh, a punched metal, a foamed metal, and the like.
• the negative electrode current collector is a metal film.
• the negative electrode current collector is a copper foil.
• the negative electrode current collector is a rolled copper foil based on a rolling method or an electrolytic copper foil based on an electrolytic method.
• the thickness of the negative electrode current collector is greater than about 1 ⁇ m or greater than about 5 ⁇ m. In some embodiments, the thickness of the negative electrode current collector is less than about 100 ⁇ m or less than about 50 ⁇ m. In some embodiments, the thickness of the negative electrode current collector is within a range between any two of the foregoing values.
• a thickness ratio of the negative electrode mixture layer to the negative electrode current collector is a thickness of one side of the negative electrode mixture layer divided by the thickness of the negative electrode current collector, and its value is not particularly limited. In some embodiments, the thickness ratio is less than 50. In some embodiments, the thickness ratio is less than 30. In some embodiments, the thickness ratio is less than 20. In some embodiments, the thickness ratio is less than 10. In some embodiments, the thickness ratio is equal to or greater than 1. In some embodiments, the thickness ratio is within a range between any two of the foregoing values. When the thickness ratio falls within the foregoing range, the capacity of the electrochemical apparatus can be ensured while heat dissipation of the negative electrode current collector during charging and discharging at high current density can be suppressed.
• the electrolyte used in the electrochemical apparatus of this application includes an electrolyte substance and a solvent for dissolving the electrolyte substance. In some embodiments, the electrolyte used in the electrochemical apparatus of this application further includes an additive.
• electrolyte includes a compound having a cyano group.
• the compound having the cyano group includes at least one of succinonitrile, glutaronitrile, adiponitrile, 1, 5-dicyanopentane, 1, 6-dicyanohexane, tetramethylsuccinonitrile, 2-methylglutaronitrile, 2, 4-dimethylglutaronitrile, 2, 2, 4, 4-tetramethylglutaronitrile, 1, 4-dicyanopentane, 1, 2-dicyanobenzene, 1, 3-dicyanobenzene, 1, 4-dicyanobenzene, ethylene glycol bis (propionitrile) ether, 3, 5-dioxa-heptanedionitrile, 1, 4-bis (cyanoethoxy) butane, diethylene glycol di (2-cyanoethyl) ether, triethylene glycol di (2-cyanoethyl) ether, tetraethylene glycol di (2-cyanoethyl) ether, 1, 3-di (2-cyanoethoxy)
• the compound having the cyano group includes an ether bond-free dinitrile compound and an ether bond-containing dinitrile compound, and a content percentage of the ether bond-free dinitrile compound is greater than a content percentage of the ether bond-containing dinitrile compound.
• the compound having the cyano group includes a dinitrile compound and a trinitrile compound, and a content percentage of the dinitrile compound is greater than a content percentage of the trinitrile compound.
• the compound having the cyano group includes a dinitrile compound and a trinitrile compound having an ether bond, and a content percentage of the dinitrile compound is greater than a content percentage of the trinitrile compound having the ether bond.
• a content percentage of the compound having the cyano group is Z%, and Z is within a range of 0.1 to 10. In some embodiments, Z is within a range of 0.5 to 8. In some embodiments, Z is within a range of 1 to 5. In some embodiments, Z is 0.1, 0.5, 1, 2, 5, 8, 10, or within a range between any two of the foregoing values.
• the content percentage Z%of the compound having the cyano group in the electrolyte and the elongation X%at the yield point of the negative electrode mixture layer satisfy: 2 ⁇ X/Z ⁇ 100. In some embodiments, 5 ⁇ X/Z ⁇ 80. In some embodiments, 10 ⁇ X/Z ⁇ 50. In some embodiments, 20 ⁇ X/Z ⁇ 30. In some embodiments, X/Z is 2, 5, 10, 20, 30, 40, 50, 60, 70, 80, 90, 100, or within a range between any two of the foregoing values.
• the rate performance and the safety performance of the electrochemical apparatus can be further improved.
• the electrolyte further includes at least one of the following compounds:
• R 1 , R 2 , R 3 , R 4 , R 5 , and R 6 each are independently hydrogen or C 1 -C 10 alkyl
• L 1 and L 2 each are independently - (CR 7 R 8 ) n -;
• R 7 and R 8 each are independently hydrogen or C 1 -C 10 alkyl
• N 1, 2, or 3.
• the fluoroethylene carbonate may act with the compound having the cyano group to form a stable protective film on the surface of the negative electrode, so as to suppress decomposition reaction of the electrolyte.
• examples of the fluoroethylene carbonate may include, but are not limited to, one or more of the following: fluoroethylene carbonate, cis-4, 4-difluoroethylene carbonate, trans-4, 4-difluoroethylene carbonate, 4, 5-difluoroethylene carbonate, 4-fluoro-4-methyl ethylene carbonate, 4-fluoro-5-methyl ethylene carbonate, and the like.
• a content percentage of the fluoroethylene carbonate is b%, and b is within a range of 0.1 to 10. In some embodiments, b is within a range of 0.5 to 8. In some embodiments, b is within a range of 1 to 5. In some embodiments, b is within a range of 2 to 4. In some embodiments, b is 0.1, 0.5, 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, or within a range between any two of the foregoing values.
• the content percentage b%of the fluoroethylene carbonate in the electrolyte and the median particle size Y ⁇ m of the negative electrode active substance satisfy: 4 ⁇ Y ⁇ b ⁇ 200. In some embodiments, 5 ⁇ Y ⁇ b ⁇ 150. In some embodiments, 10 ⁇ Y ⁇ b ⁇ 100. In some embodiments, 20 ⁇ Y ⁇ b ⁇ 50. In some embodiments, Y ⁇ b is 4, 5, 10, 20, 50, 80, 100, 120, 150, 180, 200, or within a range between any two of the foregoing values.
• the sulfur-oxygen double bond-containing compound includes at least one of the following compounds: cyclic sulfate, linear sulfate, linear sulfonate, cyclic sulfonate, linear sulfite, or cyclic sulfite.
• the cyclic sulfate includes, but is not limited to, one or more of the following: 1, 2-ethylene glycol sulfate, 1, 2-propanediol sulfate, 1, 3-propanediol sulfate, 1, 2-butanediol sulfate, 1, 3-butanediol sulfate, 1, 4-butanediol sulfate, 1, 2-pentanediol sulfate, 1, 3-pentanediol sulfate, 1, 4-pentanediol sulfate, 1, 5-pentanediol sulfate, and the like.
• the linear sulfate includes, but is not limited to, one or more of the following: dimethyl sulfate, ethyl methyl sulfate, diethyl sulfate, and the like.
• the linear sulfonate includes, but is not limited to, one or more of the following: fluorosulfonate such as methyl fluorosulfonate and ethyl fluorosulfonate, methyl methanesulfonate, ethyl methanesulfonate, butyl dimethanesulfonate, methyl 2- (methanesulfonyloxy) propionate, and ethyl 2- (methanesulfonyloxy) propionate.
• fluorosulfonate such as methyl fluorosulfonate and ethyl fluorosulfonate
• methyl methanesulfonate ethyl methanesulfonate
• butyl dimethanesulfonate butyl dimethanesulfonate
• 2- (methanesulfonyloxy) propionate methyl 2- (methanesulfonyloxy) propionat
• the cyclic sulfonate includes, but is not limited to, one or more of the following: 1, 3-propanesulfonate, 1-fluoro-1, 3-propanesulfonate, 2-fluoro-1, 3-propanesulfonate, 3-fluoro-1, 3-propanesulfonate, 1-methyl-1, 3-propanesulfonate, 2-methyl-1, 3-propanesulfonate, 3-methyl-1, 3-propanesulfonate, 1-propylene-1, 3-sulfonate, 2-propylene-1, 3-sulfonate, 1-fluoro-1-propylene-1, 3-sulfonate, 2-fluoro-1-propylene-1, 3-sulfonate, 3-fluoro-1-propylene-1, 3-sulfonate, 1-fluoro-2-propylene-1, 3-sulfonate, 2-fluoro-2-propylene-1, 3-sulfonate, 3-fluoro-2-propylene-1, 3-sulfonate, 3-
• the linear sulfite includes, but is not limited to, one or more of the following: dimethyl sulfate, ethyl methyl sulfate, diethyl sulfate, and the like.
• the cyclic sulfite includes, but is not limited to, one or more of the following: 1, 2-ethylene glycol sulfite, 1, 2-propanediol sulfite, 1, 3-propanediol sulfite, 1, 2-butanediol sulfite, 1, 3-butanediol sulfite, 1, 4-butanediol sulfite, 1, 2-pentanediol sulfite, 1, 3-pentanediol sulfite, 1, 4-pentanediol sulfite, 1, 5-pentanediol sulfite, and the like.
• the sulfur-oxygen double bond-containing compound includes a compound of Formula 2:
• W is selected from
• Ls each are independently selected from a single bond or methylene
• n 1, 2, 3, or 4;
• n 0, 1, or 2;
• p 0, 1, 2, 3, 4, 5, or 6.
• the compound of Formula 2 includes at least one of the following compounds:
• a content percentage of the sulfur-oxygen double bond-containing compound is within a range of 0.01%to 10%. In some embodiments, based on the weight of the electrolyte, the content percentage of the sulfur-oxygen double bond-containing compound is within a range of 0.05%to 8%. In some embodiments, based on the weight of the electrolyte, the content percentage of the sulfur-oxygen double bond-containing compound is within a range of 0.1%to 5%. In some embodiments, based on the weight of the electrolyte, the content percentage of the sulfur-oxygen double bond-containing compound is within a range of 0.5%to 3%.
• the content percentage of the sulfur-oxygen double bond-containing compound is within a range of 1%to 2%. In some embodiments, based on the weight of the electrolyte, the content percentage of the sulfur-oxygen double bond-containing compound is 0.01%, 0.05%, 0.1%, 0.5%, 0.8%, 1%, 2%, 5%, 8%, 10%, or within a range between any two of the foregoing values.
• Lithium difluorophosphate LiPO 2 F 2
• a content percentage of lithium difluorophosphate is 0.01%to 1.5%. In some embodiments, based on the weight of the electrolyte, the content percentage of lithium difluorophosphate is 0.05%to 1.2%. In some embodiments, based on the weight of the electrolyte, the content percentage of lithium difluorophosphate is 0.1%to 1.0%. In some embodiments, based on the weight of the electrolyte, the content percentage of lithium difluorophosphate is 0.5%to 0.8%.
• the content percentage of the lithium difluorophosphate is 0.01%, 0.05%, 0.1%, 0.15%, 0.2%, 0.25%, 0.3%, 0.35%, 0.4%, 0.45%, 0.5%, 0.8%, 1%, 1.5%, or within a range between any two of the foregoing values.
• the compound of Formula 1 includes at least one of the following compounds:
• a content percentage of the compound of Formula 1 is within a range of 0.01%to 5%. In some embodiments, based on the weight of the electrolyte, the content percentage of the compound of Formula 1 is within a range of 0.05%to 4%. In some embodiments, based on the weight of the electrolyte, the content percentage of the compound of Formula 1 is within a range of 0.1%to 3%. In some embodiments, based on the weight of the electrolyte, the content percentage of the compound of Formula 1 is within a range of 0.5%to 2%.
• the content percentage of the compound of Formula 1 is within a range of 1%to 1.5%. In some embodiments, based on the weight of the electrolyte, the content percentage of the compound of Formula 1 is 0.01%, 0.05%, 0.1%, 0.5%, 1%, 2%, 3%, 4%, 5%, or within a range between any two of the foregoing values. When the content percentage of the compound of Formula 1 falls within the foregoing range, the rate performance and the safety performance of the electrochemical apparatus can be further improved.
• the electrolyte further includes any non-aqueous solvent that is known in the art and that may be used as a solvent for the electrolyte.
• the non-aqueous solvent includes, but is not limited to, one or more of the following: cyclic carbonate, linear carbonate, cyclic carboxylic acid ester, linear carboxylic acid ester, cyclic ether, linear ether, a phosphorus-containing organic solvent, a sulfur-containing organic solvent, and an aromatic fluorine-containing solvent.
• examples of the cyclic carbonate may include, but are not limited to, one or more of the following: ethylene carbonate (EC) , propylene carbonate (PC) , and butylene carbonate.
• the cyclic carbonate has 3 to 6 carbon atoms.
• examples of the linear carbonate may include, but are not limited to, one or more of the following: dimethyl carbonate, ethyl methyl carbonate, diethyl carbonate (DEC) , methyl n-propyl carbonate, ethyl n-propyl carbonate, dipropyl carbonate, and the like.
• DEC diethyl carbonate
• linear carbonate substituted with fluorine may include, but are not limited to, one or more of the following: bis (fluoromethyl) carbonate, bis (difluoromethyl) carbonate, bis(trifluoromethyl) carbonate, bis (2-fluoroethyl) carbonate, bis (2, 2-difluoroethyl) carbonate, bis (2, 2, 2-trifluoroethyl) carbonate, 2-fluoroethyl methyl carbonate, 2, 2-difluoroethyl methyl carbonate, 2, 2, 2-trifluoroethyl methyl carbonate, and the like.
• examples of the cyclic carboxylic acid ester may include, but are not limited to, one or more of the following: ⁇ -butyrolactone and ⁇ -valerolactone.
• some hydrogen atoms of the cyclic carboxylic acid ester may be substituted with fluorine.
• examples of the linear carboxylic acid esters may include, but are not limited to, one or more of the following: methyl acetate, ethyl acetate, propyl acetate, isopropyl acetate, butyl acetate, sec-butyl acetate, isobutyl acetate, tert-butyl acetate, methyl propionate, ethyl propionate, propyl propionate, isopropyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, methyl isobutyrate, ethyl isobutyrate, methyl valerate, ethyl valerate, methyl pivalate, and ethyl pivalate.
• some hydrogen atoms of the linear carboxylic acid ester may be substituted with fluorine.
• examples of the fluorine-substituted linear carboxylic acid ester may include, but are not limited to, methyl trifluoroacetate, ethyl trifluoroacetate, propyl trifluoroacetate, butyl trifluoroacetate, 2, 2, 2-trifluoroethyl trifluoroacetate, and the like.
• examples of the cyclic ether may include, but are not limited to, one or more of the following: tetrahydrofuran, 2-methyltetrahydrofuran, 1, 3-dioxolane, 2-methyl 1, 3-dioxolane, 4-methyl 1, 3-dioxolane, 1, 3-dioxane, 1, 4-dioxane, and dimethoxypropane.
• examples of the linear ether may include, but are not limited to, one or more of the following: dimethoxymethane, 1, 1-dimethoxyethane, 1, 2-dimethoxyethane, diethoxymethane, 1, 1-diethoxyethane, 1, 2-diethoxyethane, ethoxymethoxymethane, 1, 1-ethoxymethoxyethane, and 1, 2-ethoxymethoxyethane.
• examples of the phosphorus-containing organic solvent may include, but are not limited to, one or more of the following: trimethyl phosphate, triethyl phosphate, dimethyl ethyl phosphate, methyl diethyl phosphate, ethylene methyl phosphate, ethylene ethyl phosphate, triphenyl phosphate, trimethyl phosphite, triethyl phosphite, triphenyl phosphite, tris (2, 2, 2-trifluoroethyl) phosphate, and tris (2, 2, 3, 3, 3-pentafluoropropyl) phosphate, and the like.
• examples of the sulfur-containing organic solvent may include, but are not limited to, one or more of the following: sulfolane, 2-methylsulfolane, 3-methylsulfolane, dimethyl sulfone, diethyl sulfone, ethyl methyl sulfone, methyl propyl sulfone, dimethyl sulfoxide, methyl methanesulfonate, ethyl methanesulfonate, methyl ethanesulfonate, ethyl ethanesulfonate, dimethyl sulfate, diethyl sulfate, and dibutyl sulfate.
• a portion of hydrogen atoms of the sulfur-containing organic solvent may be substituted with fluorine.
• the aromatic fluorine-containing solvent includes, but is not limited to, one or more of the following: fluorobenzene, difluorobenzene, trifluorobenzene, tetrafluorobenzene, pentafluorobenzene, hexafluorobenzene, and trifluoromethylbenzene.
• solvents used in the electrolyte of this application include cyclic carbonate, linear carbonate, cyclic carboxylic acid ester, linear carboxylic acid ester, and a combination thereof.
• the solvent used in the electrolyte of this application includes an organic solvent selected from a group consisting of the following substances: ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, n-propyl acetate, ethyl acetate, and a combination thereof.
• the solvent used in the electrolyte of this application includes ethylene carbonate, propylene carbonate, diethyl carbonate, ethyl propionate, propyl propionate, ⁇ -butyrolactone, and a combination thereof.
• examples of the additive may include, but are not limited to, one or more of the following: fluorocarbonate, carbon-carbon double bond-containing vinyl carbonate, sulfur-oxygen double bond-containing compound, and anhydride.
• a content percentage of the additive is 0.01%to 15%, 0.1%to 10%, or 1%to 5%.
• the content percentage of the propionate is 1.5 to 30 times, 1.5 to 20 times, 2 to 20 times, or 5 to 20 times of the additive.
• the additive includes one or more carbon-carbon double bond-containing vinyl carbonates.
• the carbon-carbon double bond-containing vinyl carbonate may include, but are not limited to, one or more of the following: vinylidene carbonate, methylvinylidene carbonate, ethylvinylidene carbonate, 1, 2-dimethylvinylidene carbonate, 1, 2-diethylvinylidene carbonate, fluorovinylidene carbonate, trifluoromethylvinylidene carbonate; vinylethylene carbonate, 1-methyl-2-vinylethylene carbonate, 1-ethyl-2-vinylethylene carbonate, 1-n-propyl-2-vinylethylene carbonate, 1-methyl-2-vinylethylene carbonate, 1, 1-divinylethylene carbonate, 1, 2-divinylethylene carbonate, 1, 1-dimethyl-2-methylene ethylene carbonate, 1, 1-diethyl-2-methylene ethylene carbonate, and the like.
• the carbon-carbon double bond containing vinyl carbonate may include, but are
• the additive is a combination of fluorocarbonate and carbon-carbon double bond containing vinyl carbonate. In some embodiments, the additive is a combination of fluorocarbonate and the sulfur-oxygen double bond-containing compound. In some embodiments, the additive is a combination of fluorocarbonate and a compound having 2 to 4 cyano groups. In some embodiments, the additive is a combination of fluorocarbonate and cyclic carboxylic acid ester. In some embodiments, the additive is a combination of fluorocarbonate and cyclic phosphoric anhydride. In some embodiments, the additive is a combination of fluorocarbonate and carboxylic anhydride. In some embodiments, the additive is a combination of fluorocarbonate and sulfonic anhydride. In some embodiments, the additive is a combination of fluorocarbonate and carboxylic sulfonic mixed anhydride.
• the electrolyte substance is not particularly limited, and may use any substance known as the electrolyte substance.
• lithium salts are usually used.
• the electrolyte substance may include, but are not limited to, inorganic lithium salts such as LiPF 6 , LiBF 4 , LiClO 4 , LiAlF 4 , LiSbF 6 , and LiWF 7 ; lithium tungstates such as LiWOF 5 ; lithium carboxylate salts such as HCO 2 Li, CH 3 CO 2 Li, CH 2 FCO 2 Li, CHF 2 CO 2 Li, CF 3 CO 2 Li, CF 3 CH 2 CO 2 Li, CF 3 CF 2 CO 2 Li, CF 3 CF 2 CO 2 Li, and CF 3 CF 2 CF 2 CO 2 Li; lithium sulfonate salts such as FSO 3 Li, CH 3 SO 3 Li, CH 2 FSO 3 Li, CHF 2 SO 3 Li, CF 3 SO 3 Li, CF 3 CF 2 SO 3 Li,
• the electrolyte substance is selected from the group consisting of LiPF 6 , LiSbF 6 , FSO 3 Li, CF 3 SO 3 Li, LiN (FSO 2 ) 2 , LiN(FSO 2 ) (CF 3 SO 2 ) , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , cyclic 1, 2-perfluoroethanedisulfonimide lithium, cyclic 1, 3-perfluoropropanedisulfonimide lithium, LiC (FSO 2 ) 3 , LiC (CF 3 SO 2 ) 3 , LiC (C 2 F 5 SO 2 ) 3 , LiBF 3 CF 3 , LiBF 3 C 2 F 5 , LiPF 3 (CF 3 ) 3 , LiPF 3 (C 2 F 5 ) 3 , lithium difluorooxalate borate, lithium bis (oxalate) borate, or lithium difluorobis (oxalato)
• the content percentage of the electrolyte substance is not particularly limited provided that the effect of this application is not affected.
• the total molar concentration of lithium in the electrolyte is greater than 0.3mol/L, greater than 0.4mol/L, or greater than 0.5mol/L.
• the total molar concentration of lithium in the electrolyte is less than 3mol/L, less than 2.5mol/L, or less than 2.0mol/L.
• the total molar concentration of lithium in the electrolyte is within a range between any two of the foregoing values. When the concentration in the electrolyte substance falls within the foregoing range, the amount of lithium as charged particles is not excessively small, and the viscosity can be controlled within an appropriate range, so as to ensure good conductivity.
• the electrolyte substance includes at least one salt selected from a group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate.
• the electrolyte substance includes a salt selected from a group consisting of monofluorophosphate, oxalate, and fluorosulfonate.
• the electrolyte substance includes a lithium salt.
• the content percentage of the salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate is greater than 0.01%or greater than 0.1%.
• the content percentage of the salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate is less than 20%or less than 10%. In some embodiments, the content percentage of the salt selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate is within a range between any two of the foregoing values.
• the electrolyte substance includes more than one substance selected from the group consisting of monofluorophosphate, borate, oxalate, and fluorosulfonate and more than one other salt different from the more than one substance.
• the other salt include lithium salts exemplified above, and in some embodiments, are LiPF 6 , LiN (FSO 2 ) (CF 3 SO 2 ) , LiN (CF 3 SO 2 ) 2 , LiN (C 2 F 5 SO 2 ) 2 , lithium cyclic 1, 2-perfluoroethane disulfonimide, lithium cyclic 1, 3-perfluoropropane disulfonimide, LiC (FSO 2 ) 3 , LiC (CF 3 SO 2 ) 3 , LiC (C 2 F 5 SO 2 ) 3 , LiBF 3 CF 3 , LiBF 3 C 2 F 5 , LiPF 3 (CF 3 ) 3 , and LiPF 3 (C 2 F 5 ) 3 .
• LiPF 6 LiN (
• the content percentage of the other salt is greater than 0.01%or greater than 0.1%. In some embodiments, based on the weight of the electrolyte substance, the content percentage of the other salt is less than 20%, less than 15%, or less than 10%. In some embodiments, the content percentage of the other salt is within a range between any two of the foregoing values. The other salt having the foregoing content helps balance the conductivity and viscosity of the electrolyte.
• additives such as a negative electrode film forming agent, a positive electrode protection agent, and an overcharge prevention agent may be included as necessary.
• an additive generally used in non-aqueous electrolyte secondary batteries may be used, and examples thereof may include, but are not limited to, vinylidene carbonate, succinic anhydride, biphenyls, cyclohexylbenzene, 2, 4-difluoroanisole, propane sulfonate, propylene sulfonate, and the like.
• the additives may be used alone or in any combination.
• the content percentage of these additives in the electrolyte is not particularly limited and may be properly set according to the types of the additives or the like. In some embodiments, based on the weight of the electrolyte, the content percentage of the additive is less than 5%, within a range of 0.01%to 5%, or within a range of 0.2%to 5%.
• the positive electrode includes a positive electrode current collector and a positive electrode active substance layer disposed on one or both surfaces of the positive electrode current collector.
• the positive electrode active substance layer includes a positive electrode active substance.
• the positive electrode active substance layer may be one or more layers. Each layer of the multilayer positive electrode active substances may contain the same or different positive electrode active substances.
• the positive electrode active substance is any material capable of reversibly intercalating and deintercalating metal ions such as lithium ions.
• the type of the positive electrode active substance is not particularly limited provided that metal ions (for example, lithium ions) can be electrochemically absorbed and released.
• the positive electrode active substance is a material that contains lithium and at least one transition metal.
• the positive electrode active substance may include, but are not limited to, lithium transition metal composite oxides and lithium-containing transition metal phosphate compounds.
• transition metals in the lithium transition metal composite oxide include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, and the like.
• the lithium transition metal composite oxides include lithium cobalt composite oxides such as LiCoO 2 , lithium nickel composite oxides such as LiNiO 2 , lithium manganese composite oxides such as LiMnO 2 , LiMn 2 O 4 , and Li 2 MnO 4 , and lithium nickel manganese cobalt composite oxides such as LiNi 1/3 Mn 1/3 Co 1/3 O 2 , and LiNi 0.5 Mn 0.3 Co 0.2 O 2 , where a portion of transition metal atoms serving as a main body of these lithium transition metal composite oxides is substituted with other elements such as Na, K, B, F, Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Si, Nb, Mo, Sn, and W.
• lithium transition metal composite oxide may include, but are not limited to, LiNi 0.5 Mn 0.5 O 2 , LiNi 0.85 Co 0.10 Al 0.05 O 2 , LiNi 0.33 Co 0.33 Mn 0.33 O 2 , LiNi 0.45 Co 0.10 Al 0.45 O 2 , LiMn 1.8 Al 0.2 O 4 , and LiMn 1.5 Ni 0.5 O 4.
• Examples of a combination of lithium transition metal composite oxides include, but are not limited to, a combination of LiCoO 2 and LiMn 2 O 4, where a portion of Mn in LiMn 2 O 4 may be substituted with a transition metal (for example, LiNi 0.33 Co 0.33 Mn 0.33 O 2 ) and a portion of Co in LiCoO 2 may be substituted with a transition metal.
• transition metals in the lithium-containing transition metal phosphate compound include V, Ti, Cr, Mn, Fe, Co, Ni, Cu, and the like.
• the lithium-containing transition metal phosphate compound includes iron phosphates such as LiFePO 4 , Li 3 Fe 2 (PO 4 ) 3 , and LiFeP 2 O 7 , and cobalt phosphates such as LiCoPO 4 , where a portion of transition metal atoms serving as a main body of these lithium transition metal phosphate compounds are substituted with other elements such as Al, Ti, V, Cr, Mn, Fe, Co, Li, Ni, Cu, Zn, Mg, Ga, Zr, Nb, and Si.
• the positive electrode active substance includes lithium phosphate, which can improve the continuous charging property of the electrochemical apparatus.
• the use of lithium phosphates is not limited.
• the positive electrode active substance and lithium phosphates are used in combination.
• the content percentage of the lithium phosphate is greater than 0.1%, greater than 0.3%, or greater than 0.5%relative to the weight of the positive electrode active substance and lithium phosphate.
• the content percentage of the lithium phosphate is less than 10%, less than 8%, or less than 5%relative to the weight of the positive electrode active substance and lithium phosphate.
• the content percentage of the lithium phosphate is within a range between any two of the foregoing values.
• a substance different from a composition of the positive electrode active substance may be adhered onto the surface of the positive electrode active substance.
• the surface adhesion substance include, but are not limited to, oxides such as aluminum oxide, silicon dioxide, titanium dioxide, zirconium oxide, magnesium oxide, calcium oxide, boron oxide, antimony oxide, and bismuth oxide; sulphates such as lithium sulfate, sodium sulfate, potassium sulfate, magnesium sulfate, calcium sulfate, and aluminum sulfate; carbonates such as lithium carbonate, calcium carbonate, and magnesium carbonate; carbon; and so on.
• These surface adhesion substances may be adhered to the surface of the positive electrode active substance by using the following methods: a method of dissolving or suspending the surface adhesion substance in the solvent to infiltrate into the positive electrode active substance and then performing drying; a method of dissolving or suspending a surface adhesion substance precursor in the solvent to infiltrate into the positive electrode active substance and then performing heating or the like to implement reaction of the surface adhesion substance; and a method of adding the surface adhesion substance to a positive electrode active substance precursor and performing sintering simultaneously.
• a method for mechanical adhesion of a carbon material for example, activated carbon
• the content percentage of the surface adhesion substance is greater than 0.1ppm, greater than 1ppm, or greater than 10ppm. In some embodiments, based on the weight of the positive electrode active substance layer, the content percentage of the surface adhesion substance is less than 10%, less than 8%, or less than 5%. In some embodiments, based on the weight of the positive electrode active substance layer, the content percentage of the surface adhesion substance is within a range between any two of the foregoing values.
• Adhering a substance to the surface of the positive electrode active substance can suppress oxidation reaction of the electrolyte on the surface of the positive electrode active substance and improve the service life of the electrochemical apparatus.
• An excessively small amount of substance adhered to the surface cannot make the effect fully displayed while an excessively large amount of substance adhered to the surface prevents intercalation and deintercalation of lithium ions to increase the resistance sometimes.
• positive electrode active substance that has a composition different from the positive electrode active substance and that is adhered to the surface of the positive electrode active substance is also called “positive electrode active substance” .
• the shapes of particles of the positive electrode active substance include, but are not limited to, block, polyhedron, spherical, ellipsoidal, plate, needle, column, and the like.
• the positive electrode active substance particles include primary particles, secondary particles, or a combination thereof.
• the primary particles may agglomerate to form the secondary particles.
• the tap density of the positive electrode active substance is greater than 0.5g/cm 3 , greater than 0.8g/cm 3 , or greater than 1.0g/cm 3 .
• the amount of the dispersion medium, the amount of the conductive material, and the amount of the positive electrode binder that are required for forming the positive electrode active substance layer can be suppressed, thereby ensuring a filling rate of the positive electrode active substance and the capacity of the electrochemical apparatus.
• Using a composite oxide powder with a high tap density can form a positive electrode active substance layer with a high density.
• a larger tap density incidates being more preferable, and there is no particular upper limit.
• the tap density of the positive electrode active substance is less than 4.0g/cm 3 , less than 3.7g/cm 3 , or less than 3.5g/cm 3 .
• the tap density of the positive electrode active substance has the upper limit as described above, an decrease in load characteristics can be suppressed.
• the tap density of the positive electrode active substance can be calculated in the following manner: placing 5g to 10g of the positive electrode active substance powder into a 10mL glass measuring cylinder and tapping 200 times at 20mm stroke to obtain a powder filling density (the tap density) .
• the median particle size (D50) of the positive electrode active substance particles is a primary particle size of the positive electrode active substance particles.
• the median particle size (D50) of the positive electrode active substance particles is a secondary particle size of the positive electrode active substance particles.
• the median particle size (D50) of the positive electrode active substance particles is greater than 0.3 ⁇ m, greater than 0.5 ⁇ m, greater than 0.8 ⁇ m, or greater than 1.0 ⁇ m. In some embodiments, the median particle size (D50) of the positive electrode active substance particles is less than 30 ⁇ m, less than 27 ⁇ m, less than 25 ⁇ m, or less than 22 ⁇ m. In some embodiments, the median particle size (D50) of the positive electrode active substance particles is within a range between any two of the foregoing values. When the median particle size (D50) of the positive electrode active substance particles falls within the foregoing range, a positive electrode active substance with a high tap density can be implemented, and performance degradation of the electrochemical apparatus can be suppressed.
• problems such as stripes can be prevented during preparation of the positive electrode of the electrochemical apparatus (that is, when the positive electrode active substance, the conductive material, the binder, and the like are made into a slurry with a solvent and the slurry is applied in a thin-film form) .
• the positive electrode active substance, the conductive material, the binder, and the like are made into a slurry with a solvent and the slurry is applied in a thin-film form.
• more than two types of positive electrode active substances having different median particle size s are mixed, to further improve the filling property during preparation of the positive electrode.
• the median particle size (D50) of the positive electrode active substance particles can be measured by using a laser diffraction/scattering particle size distribution tester: when LA-920 manufactured by HORIBA is used as a particle size distribution tester, using a 0.1%sodium hexametaphosphate aqueous solution as a dispersion medium for testing, and measuring a result at an refractive index of 1.24 after ultrasonic dispersion for five minutes.
• the average primary particle size of the positive electrode active substance is greater than 0.05 ⁇ m, greater than 0.1 ⁇ m, or greater than 0.5 ⁇ m. In some embodiments, the average primary particle size of the positive electrode active substance is less than 5 ⁇ m, less than 4 ⁇ m, less than 3 ⁇ m, or less than 2 ⁇ m. In some embodiments, the average primary particle size of the positive electrode active substance is within a range between any two of the foregoing values.
• the average primary particle size of the positive electrode active substance falls within the foregoing range, the powder filling property and the specific surface area can be ensured, performance degradation of the battery can be suppressed, and moderate crystallinity can be implemented, thereby ensuring reversibility of charging and discharging of the electrochemical apparatus.
• the average primary particle size of the positive electrode active substance may be obtained by observing an image from a scanning electron microscope (SEM) : in the SEM image magnified 10000 times, for any 50 primary particles, obtaining longest values of slices obtained on the left and right boundary lines of the primary particles relative to the horizontal straight line, and calculating an average value to obtain the average primary particle size.
• SEM scanning electron microscope
• the specific surface area (BET) of the positive electrode active substance is greater than 0.1m 2 /g, greater than 0.2m 2 /g, or greater than 0.3m 2 /g. In some embodiments, the specific surface area (BET) of the positive electrode active substance is less than 50m 2 /g, less than 40m 2 /g, or less than 30m 2 /g. In some embodiments, the specific surface area (BET) of the positive electrode active substance is within a range between any two of the foregoing values. When the specific surface area (BET) of the positive electrode active substance falls within the foregoing range, the performance of the electrochemical apparatus can be ensured, and the positive electrode active substance can have a good coating property.
• the specific surface area (BET) of the positive electrode active substance can be measured by using the following method: using a surface area meter (for example, a full-automatic surface area tester manufactured by OHKURA or RIKEN) to perform predrying on the sample at 150°C for 30 minutes when nitrogen flows, using nitrogen-helium mixed gas whose relative pressure value of nitrogen is accurately adjusted to 0.3 with respect to atmospheric pressure, and conducting tests by using the nitrogen adsorption BET single-point method based on the air flow method.
• a surface area meter for example, a full-automatic surface area tester manufactured by OHKURA or RIKEN
• the type of positive electrode conductive material is not limited, and any known conductive material may be used.
• the positive electrode conductive material may include, but are not limited to, graphite such as natural graphite and artificial graphite; carbon black such as acetylene black; carbon materials including amorphous carbon such as acicular coke; carbon nanotube; graphene; and the like.
• the positive electrode conductive material may be used alone or in any combination.
• the content percentage of the positive electrode conductive material is greater than 0.01%, greater than 0.1%, or greater than 1%. In some embodiments, based on the weight of the positive electrode active substance layer, the content percentage of the positive electrode conductive material is less than 10%, less than 8%, or less than 5%. When the content percentage of the positive electrode conductive material falls within the foregoing range, sufficient conductivity and the capacity of the electrochemical apparatus can be ensured.
• the type of the positive electrode binder used during preparation of the positive electrode active substance layer is not particularly limited, and in the case of using the coating method, any material that can be dissolved or dispersed in a liquid medium used in the preparation of the electrode is acceptable.
• the positive electrode binder may include, but are not limited to, one or more of the following: a resin-based polymer such as polyethylene, polypropylene, polyethylene glycol terephthalate, polymethyl methacrylate, polyimide, aromatic polyamide, cellulose, or nitrocellulose; a rubber polymer such as styrene-butadiene rubber (SBR) , isoprene rubber, polybutadiene rubber, fluorine rubber, acrylonitrile ⁇ butadiene rubber (NBR) , or ethylene ⁇ propylene rubber; styrene ⁇ butadiene ⁇ styrene block copolymer or hydride thereof; a thermoplastic elastomeric polymer such as ethylene ⁇ propylene ⁇ diene ter
• the content percentage of the positive electrode binder is greater than 0.1%, greater than 1%, or greater than 1.5%. In some embodiments, based on the weight of the positive electrode active substance layer, the content percentage of the positive electrode binder is less than 10%, less than 8%, less than 4%, or less than 3%. When the content percentage of the positive electrode binder falls within the foregoing range, the positive electrode can have good conductivity and sufficient mechanical strength, and the capacity of the electrochemical apparatus can be ensured.
• the type of the solvent used for forming the positive electrode slurry is not limited provided that the solvent is capable of dissolving or dispersing the positive electrode active substance, the conductive material, the positive electrode binder, and the thickener used as required.
• the solvent used to form the positive electrode slurry may include any of an aqueous solvent and an organic solvent.
• the aqueous medium may include, but are not limited to, water, a mixed medium of alcohol and water, and the like.
• Examples of the organic medium may include, but are not limited to, aliphatic hydrocarbons such as hexane; aromatic hydrocarbons such as benzene, toluene, xylene, and methylnaphthalene; heterocyclic compounds such as quinoline and pyridine; ketones such as acetone, methyl ethyl ketone, and cyclohexanone; esters such as methyl acetate and methyl acrylate; amines such as diethylenetriamine, and N, N-dimethylaminopropylamine; ethers such as diethyl ether, propylene oxide, and tetrahydrofuran (THF) ; amides such as N-methylpyrrolidone (NMP) , dimethylformamide, and dimethylacetamide; aprotic polar solvents such as hexamethylphosphoramide and dimethyl sulfoxide; and so on.
• aliphatic hydrocarbons such as hexane
• the thickener is usually used to adjust viscosity of the slurry.
• the thickener and styrene-butadiene rubber (SBR) emulsion may be used for making the slurry.
• SBR styrene-butadiene rubber
• the type of the thickener is not particularly limited, and examples of the thickener may include, but are not limited to, carboxymethyl cellulose, methyl cellulose, hydroxymethyl cellulose, ethyl cellulose, polyvinyl alcohol, oxidized starch, phosphorylated starch, casein, salt thereof, and the like.
• the thickener may be used alone or in any combination.
• the content percentage of the thickener is greater than 0.1%, greater than 0.2%, or greater than 0.3%. In some embodiments, based on the weight of the positive electrode active substance layer, the content percentage of the thickener is less than 5%, less than 3%, or less than 2%. In some embodiments, based on the weight of the positive electrode active substance layer, the content percentage of the thickener is within a range between any two of the foregoing values. When the content percentage of the thickener falls within the foregoing range, a good coating property of the positive electrode slurry can be ensured, and a decrease in the capacity of the electrochemical apparatus and an increase in the resistance can be suppressed.
• the content percentage of the positive electrode active substance is greater than 80%, greater than 82%, or greater than 84%. In some embodiments, based on the weight of the positive electrode active substance layer, the content percentage of the positive electrode active substance is less than 99%or less than 98%. In some embodiments, based on the weight of the positive electrode active substance layer, the content percentage of the positive electrode active substance is within a range between any two of the foregoing values. When the content percentage of the positive electrode active substance falls within the foregoing range, the capacity of the positive electrode active substance in the positive electrode active substance layer can be ensured while the strength of the positive electrode can be maintained.
• the positive electrode active substance layer obtained by coating and drying can be pressed by using a manual press, a roller, or the like.
• the density of the positive electrode active substance layer is greater than 1.5g/cm 3 , greater than 2g/cm 3 , or greater than 2.2g/cm 3 .
• the density of the positive electrode active substance layer is less than 5g/cm 3 , less than 4.5g/cm 3 , or less than 4g/cm 3 .
• the density of the positive electrode active substance layer is within a range between any two of the foregoing values. When the density of the positive electrode active substance layer falls within the foregoing range, the electrochemical apparatus can have good charge/discharge performance and an increase in the resistance can be suppressed.
• the thickness of the positive electrode active substance layer is the thickness of the positive electrode active substance layer on either side of the positive electrode current collector. In some embodiments, the thickness of the positive electrode active substance layer is greater than 10 ⁇ m or greater than 20 ⁇ m. In some embodiments, the thickness of the positive electrode active substance layer is less than 500 ⁇ m or less than 450 ⁇ m.
• the positive electrode active substance may be manufactured by using a commonly used method for manufacturing an inorganic compound.
• a spherical or ellipsoidal positive electrode active substance the following preparation method may be used: dissolving or pulverizing and dispersing the raw material of transition metal in a solvent such as water; adjusting the pH while stirring; making and reclaiming spherical precursors; after drying as needed, adding Li sources such as LiOH, Li 2 CO 3 , and LiNO 3 ; and performing sintering at a high temperature, to obtain the positive electrode active substance.
• the type of positive electrode current collector is not particularly limited and may be any known material used as the positive electrode current collector.
• the positive electrode current collector may include, but are not limited to, metal materials such as aluminum, stainless steel, a nickel plating layer, titanium, and tantalum; and carbon materials such as a carbon cloth and carbon paper.
• the positive electrode current collector is a a metal material.
• the positive electrode current collector is aluminum.
• the form of the positive electrode current collector is not particularly limited.
• the positive electrode current collector may be in forms, including but not limited to a metal foil, a metal cylinder, a metal coil, a metal plate, a metal foil, a sheet metal mesh, a punched metal, a foamed metal, and the like.
• the positive electrode current collector is a carbon material
• the form of the positive electrode current collector may include, but is not limited to, a carbon plate, a carbon film, a carbon cylinder, and the like.
• the positive electrode current collector is a metal foil.
• the metal foil is a mesh. The thickness of the metal foil is not particularly limited.
• the thickness of the metal foil is greater than 1 ⁇ m, greater than 3 ⁇ m, or greater than 5 ⁇ m. In some embodiments, the thickness of the metal foil is less than 1 mm, less than 100 ⁇ m, or less than 50 ⁇ m. In some embodiments, the thickness of the metal foil is within a range between any two of the foregoing values.
• the surface of the positive electrode current collector may include an electrically-conductive additive.
• the electrically-conductive additive may include, but are not limited to, carbon and precious metals such as gold, platinum, and silver.
• a thickness ratio of the positive electrode active substance layer to the positive electrode current collector is a thickness of one side of the positive electrode active substance layer divided by the thickness of the positive electrode current collector, and its value is not particularly limited. In some embodiments, the thickness ratio is less than 50, less than 30, or less than 20. In some embodiments, the thickness ratio is greater than 0.5, greater than 0.8, or greater than 1. In some embodiments, the thickness ratio is within a range between any two of the foregoing values. When the thickness ratio falls within the foregoing range, heat dissipation of the positive electrode current collector during charging and discharging at high current density can be suppressed, and the capacity of the electrochemical apparatus can be ensured.
• the positive electrode may be prepared by forming, on a current collector, a positive electrode active substance layer containing a positive electrode active substance and a binder.
• the positive electrode using the positive electrode active substance can be prepared by using a conventional method: dry mixing the positive electrode active substance, the binder, and the conductive material and the thickener that are to be used as required to form a sheet, and pressing the resulting sheet onto the positive electrode current collector; or dissolving or dispersing these materials in a liquid medium to make a slurry, and applying the slurry onto the positive electrode current collector, followed by drying, to form a positive electrode active substance layer on the current collector. Then, the positive electrode is obtained.
• a separator is usually provided between the positive electrode and the negative electrode.
• the electrolyte of this application usually permeates the separator.
• the material and shape of the separator are not particularly limited provided that the separator does not significantly affect the effect of this application.
• the separator may be a resin, glass fiber, inorganic substance, or the like that is formed of a material stable to the electrolyte of this application.
• the separator includes a porous sheet or nonwoven fabric-like material having an excellent fluid retention property, or the like.
• Examples of the material of the resin or glass fiber separator may include, but are not limited to, polyolefin, aromatic polyamide, polytetrafluoroethylene, polyethersulfone, and the like.
• the polyolefin is polyethylene or polypropylene.
• the polyolefin is polypropylene.
• the material of the separator may be used alone or in any combination.
• the separator may alternatively be a material formed by laminating the foregoing materials, and examples thereof include, but are not limited to, a three-layer separator formed by laminating polypropylene, polyethylene, and polypropylene in order.
• Examples of the material of the inorganic substance may include, but are not limited to, oxides such as aluminum oxide and silicon dioxide, nitrides such as aluminum nitride and silicon nitride, and sulfates (for example, barium sulfate and calcium sulfate) .
• the form of the inorganic substance may include, but are not limited to, a granular or fibrous form.
• the form of the separator may be a thin-film form, and examples thereof include, but are not limited to, a non-woven fabric, a woven fabric, a microporous film, and the like.
• the separator has a pore diameter of 0.01 ⁇ m to 1 ⁇ m and a thickness of 5 ⁇ m to 50 ⁇ m.
• the following separator may alternatively be used: a separator that is obtained by using a resin-based binder to form a composite porous layer containing the inorganic particles on the surface of the positive electrode and/or the negative electrode, for example, a separator that is obtained by using fluororesin as a binder to form a porous layer on both surfaces of the positive electrode with alumina particles whose particle size s of 90%particles are less than 1 ⁇ m.
• the thickness of the separator is random. In some embodiments, the thickness of the separator is greater than 1 ⁇ m, greater than 5 ⁇ m, or greater than 8 ⁇ m. In some embodiments, the thickness of the separator is less than 50 ⁇ m, less than 40 ⁇ m, or less than 30 ⁇ m. In some embodiments, the thickness of the separator is within a range between any two of the foregoing values. When the thickness of the separator falls within the foregoing range, the insulation property and the mechanical strength can be ensured, and the rate performance and the energy density of the electrochemical apparatus can be ensured.
• the porosity of the separator is random. In some embodiments, the porosity of the separator is greater than 10%, greater than 15%, or greater than 20%. In some embodiments, the porosity of the separator is less than 60%, less than 45%, or less than 40%. In some embodiments, the porosity of the separator is within a range between any two of the foregoing values. When the porosity of the separator falls within the foregoing range, the insulation property and the mechanical strength can be ensured and the film resistance can be suppressed, so that the electrochemical apparatus has good rate performance.
• the average pore diameter of the separator is also random. In some embodiments, the average pore diameter of the separator is less than 0.5 ⁇ m or less than 0.2 ⁇ m. In some embodiments, the average pore diameter of the separator is greater than 0.05 ⁇ m. In some embodiments, the average pore diameter of the separator is within a range between any two of the foregoing values. If the average pore diameter of the separator exceeds the foregoing range, a short circuit is likely to occur. When the average pore diameter of the separator falls within the foregoing range, the film resistance can be suppressed and the short circuit is prevented, so that the electrochemical apparatus has good rate performance.
• the components of the electrochemical apparatus include an electrode assembly, a collector structure, an outer packing case, and a protection element.
• the electrode assembly may be any one of a laminated structure in which the positive electrode and the negative electrode are laminated with the separator interposed therebetween, and a structure in which the positive electrode and the negative electrode are wound in a swirl shape with the separator interposed therebetween.
• a mass percentage of the electrode assembly (occupancy of the electrode assembly) in the internal volume of the battery is greater than 40%or greater than 50%.
• the occupancy of the electrode assembly is less than 90%or less than 80%.
• the occupancy of the electrode assembly is within a range between any two of the foregoing values. When the occupancy of the electrode assembly falls within the foregoing range, the capacity of the electrochemical apparatus can be ensured, and a decrease in repeated charge/discharge performance and high temperature storage property caused by an increasing internal pressure can be suppressed.
• the collector structure is not particularly limited. In some embodiments, the collector structure is a structure that reduces the resistance of a wiring portion and a bonding portion.
• the electrode assembly is the foregoing laminated structure, a structure in which metal core portions of the electrode layers are bundled and welded to terminals can be used. An increase in an electrode area of one layer causes a higher internal resistance; therefore, it is also acceptable that more than two terminals are provided in the electrode to decrease the resistance.
• the electrode assembly has the foregoing winding structure, more than two lead structures are provided on each of the positive electrode and the negative electrode, and are bundled on the terminals, so as to reduce the internal resistance.
• the material of the outer packing case is not particularly limited provided that the material is a substance stable to the electrolyte in use.
• the outer packing case may use, but is not limited to a nickel-plated steel plate, stainless steel, metals such as aluminium, aluminum alloy, or magnesium alloy, or laminated films of resin and aluminum foil.
• the outer packing case is made of metal including aluminum or an aluminum alloy, or be made of a laminated film.
• the metal outer packing case includes, but is not limited to, a sealed packaging structure formed by depositing metals through laser welding, resistance welding, and ultrasonic welding; or a riveting structure formed by using the foregoing metal or the like with a resin pad disposed therebetween.
• the outer packing case using the laminated film includes, but is not limited to, a sealed packaging structure or the like formed by thermally adhering resin layers. In order to improve the sealing property, a resin different from the resin used in the laminated film may be sandwiched between the resin layers.
• a resin having a polar group or a modified resin into which a polar group is introduced may be used as the sandwiched resin due to bonding of the metal and the resin.
• the shape of the outer packing case may be in any random shape, for example, in any one of a cylindrical shape, a square shape, a laminated shape, a button shape, and the like.
• the protection element may use a positive temperature coefficient (PTC) , a temperature fuse, and a thermistor whose resistance increases during abnormal heat release or excessive current flows, a valve (current cutoff valve) for cutting off a current flowing in a circuit by sharply increasing an internal pressure or an internal temperature of a battery during abnormal heat release or excessive current flow, or the like.
• PTC positive temperature coefficient
• the protection element may be selected from elements that do not operate in conventional high-current use scenarios, or the apparatus may be so designed as not to cause abnormal heat release or thermal runaway even in the absence of the protection element.
• the electrochemical apparatus in this application includes any apparatus on which electrochemical reactions occur. Its specific examples include all kinds of primary batteries, secondary batteries, fuel batteries, solar batteries, or capacitors.
• the electrochemical apparatus is a lithium secondary battery, including a lithium metal secondary battery or a lithium ion secondary battery.
• This application further provides an electronic apparatus, including the electrochemical apparatus in this application.
• the electrochemical apparatus in this application can be used in any electronic apparatus known in the prior art.
• the electrochemical apparatus in this application may be used in, but being not limited to, a notebook computer, a pen-input computer, a mobile computer, an e-book player, a portable phone, a portable fax, a portable copier, a portable printer, a headphone stereo, a video recorder, an LCD TV, a handy cleaner, a portable CD player, a mini disk, a transceiver, an electronic notebook, a calculator, a memory card, a portable recorder, a radio, a backup power supply, a motor, a vehicle, a motorcycle, a power assisted cycle, a bicycle, a lighting appliance, a toy, a game player, a clock, an electric tool, a flash lamp, a camera, a large household battery, a lithium-ion capacitor, or the like.
• Styrene-butadiene rubber (SBR) 2 Acrylate styrene-butadiene rubber copolymer 3 Styrene acrylate copolymer 4 Mixture of chlorotrifluoroethylene and styrene-butadiene rubber 5 Mixture of HFP (hexafluoropropylene) and styrene-butadiene rubber
• Lithium cobaltate (LiCoO 2 ) , conductive material (Super-P) , and polyvinylidene fluoride (PVDF) were mixed in N-methylpyrrolidone (NMP) based on a mass ratio of 95%: 2%: 3%. After stirring evenly, a positive electrode slurry was obtained. The positive electrode slurry was applied onto an aluminum foil of 12 ⁇ m. After steps of drying, cold pressing, cutting, and lug welding, the positive electrode was obtained.
• a polyethylene (PE) porous polymer film was used as the separator.
• the resulting positive electrode, separator, and negative electrode were wound in order and placed in an outer packing foil, leaving a liquid injection hole. After the steps of injecting the electrolyte into the liquid injection hole, packaging, chemical conversion, and testing capacitance, the lithium-ion battery was obtained.
• the lithium-ion battery was discharged to 3.0V at 0.2C, and after standing for five minutes, was charged to 4.4V at 0.5C and then charged to 0.05C at a constant voltage. After standing for five minutes, the discharge rate was adjusted and discharge tests were conducted separately at 0.2C and 5.0C, to obtain the discharge capacity. The capacity obtained at a rate of 5.0C was compared with the capacity obtained at 0.2C, to obtain a ratio. The ratio was used to represent the rate performance of the lithium-ion battery.
• the lithium-ion battery was kept standing for 30 minutes, and its thickness T1 was measured. Then, the temperature was started to rise at a temperature rise rate of 5°C/min. When the temperature rose to 130°C, the thickness T2 of the lithium-ion battery was measured after standing for 30 minutes.
• the thickness swelling rate of the lithium-ion battery was calculated by using the following formula:
• Thickness swelling rate [ (T2-T1) /T1] ⁇ 100%
• Table 1 shows the impact of the elongation X%at the yield point of the negative electrode mixture layer, the median particle size Y ⁇ m of the negative electrode active substance, and their relationship on the rate performance and the thickness swelling rate of the lithium-ion battery.
• Table 2 shows the impact of the rubber on the rate performance and the thickness swelling rate of the lithium-ion battery. Examples 2-1 to 2-9 differ from Example 1-1 only in the parameters listed in Table 2.
• the results show that the elongation at the yield point of the negative electrode mixture layer can be adjusted by using different rubber.
• the elongation at the yield point of the negative electrode mixture layer is within a range of 10%to 30%and Y is within a range of 1 to 50, the rate performance of the lithium-ion battery can be further improved and the thickness swelling rate of the lithium-ion battery can be reduced.
• Table 3 shows the impact of trace metals in the negative electrode active substance on the rate performance and the thickness swelling rate of the lithium-ion battery. Examples 3-1 to 3-8 differ from Example 1-1 only in the parameters listed in Table 3.
• Table 4 shows the impact of the compound having the cyano group on improvement of the rate performance and the thickness swelling rate of the lithium-ion battery. Examples 4-1 to 4-6 differ from Example 1-1 only in the parameters listed in Table 4.
• Table 5 shows the impact of the electrolyte composition on the rate performance and the thickness swelling rate of the lithium-ion battery. Examples 5-1 to 5-31 differ from Example 1-1 only in the parameters listed in Table 5.
• the results show that, based on that the elongation X%at the yield point of the negative electrode mixture layer and the median particle size Y ⁇ m of the negative electrode active substance satisfy 0.1 ⁇ X/Y ⁇ 30 and the electrolyte includes the compound having the cyano group, when the electrolyte further contains fluoroethylene carbonate, the sulphur-oxygen double bond-containing compound, lithium difluorophosphate, and/or the compound of Formula 1, the rate performance of the lithium-ion battery can be further improved and the thickness swelling rate of the lithium-ion battery can be reduced to improve the safety performance of the lithium-ion battery.
• Table 6 shows the impact of the relationship between the median particle size Y ⁇ m of the negative electrode active substance and the content percentage b%of fluoroethylene carbonate in the electrolyte on the rate performance and the thickness swelling rate of the lithium-ion battery. Examples 6-1 to 6-9 differ from Example 5-1 only in the parameters listed in Table 6.
• the results show that when the content percentage of fluoroethylene carbonate in the electrolyte is 0.1%to 10%, the rate performance of the lithium-ion battery can be further improved, and the thickness swelling rate of the lithium-ion battery can be reduced to improve the safety performance of the lithium-ion battery.
• the relationship between the median particle size Y ⁇ m of the negative electrode active substance and the content percentage b%of fluoroethylene carbonate in the electrolyte satisfy 4 ⁇ Y ⁇ b ⁇ 200, the rate performance of the lithium-ion battery can be further improved and the thickness swelling rate of the lithium-ion battery can be reduced to improve the safety performance of the lithium-ion battery.
• Table 7 shows the impact of the relationship between the elongation X%at the yield point of the negative electrode mixture layer and the content percentage Z%of the compound having the cyano group in the electrolyte on the rate performance and the thickness swelling rate of the lithium-ion battery.
• Examples 7-1 to 7-6 differ from Example 1-1 only in the parameters listed in Table 7.
• references to “embodiments” , “an embodiment” , “another example” , “examples” , “specific examples” , or “some examples” means that at least one embodiment or example in this application includes a specific feature, structure, material, or characteristic described in this embodiment or example. Therefore, descriptions that appear in various parts of this specification, such as “in some embodiments” , “in the embodiments” , “in an embodiment” , “in another example” , “in an example” , “in a specific example” , or “examples” do not necessarily reference the same embodiment or example in this application.
• a specific feature, structure, material, or property herein may be combined in any appropriate manner in one or more embodiments or examples.

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